The present invention relates to an ink receptacle for an ink on-demand type ink jet printer in which an ink reservoir of an ink jet head is mounted on a carriage.
Well known in the printing art is an ink jet printer of the type in which an ink jet head is mounted on a carriage and, while the carriage is moved relative to a paper, ink drops are ejected from the ink jet head to print out data on the paper. For example, Japanese Unexamined Patent Publication (Kokai) No. 57-18265 discloses an ink jet printer having a first reservoir, or tank, which is mounted in a stationary portion of the printer and a second reservoir, or tank, which is mounted on a carriage. The first and second ink reservoirs are fluidly communicated to each other by a flexible tube. Although such a prior art printer allows the total reservoir volume to be increased, it brings about various problems such as slipping out of the flexible tube and leakage of ink at the interconnected portions, while requiring an extra space for the movement of the tube. Meanwhile, Japanese Unexamined Patent Publication (Kokai) No. 58-147372 describes an ink jet printer which eliminates the need for the flexible tube by mounting an ink reservoir (cartridge) and an ink jet head on a carriage. The problem with this tube-less scheme is that it needs an opening for drawing the same amount of air as ink consumed into the reservoir, the opening inviting leakage of ink due to vibration and evaporation of ink. These problems may be solved by an implementation wherein the reservoir (cartridge) is constructed by use of a flexible film, as disclosed in Japanese Unexamined Patent Publication (Kokai) No. 52-110633. Nevertheless, unless extra structures such as a damping structure are built in the head, the film type scheme fails to prevent data from being printed out with high quality because the pressure inside the tank is variable responsive to reciprocation of the carriage.
As discussed above, prior art ink on-demand printers of the type having an ink reservoir mounted on a carriage have a drawback that pressure variations due to reciprocation of a carriage cannot be prevented unless the volume of ink is severely restricted or the tank is provided with a complicated structure.